It's inevitable—another year, another macOS version (I am still not used to typing "macOS"), and another build up to a significant SuperDuper! release. Sorry I haven't been blogging the whole way through, but it's been busy, and I just haven't had the time.

As of this morning, we have a release date - September 25th. So, for those asking (and there are a lot of you), let's talk about High Sierra. Lucky 13! Woo!


First, we'll definitely be supporting APFS. That work has been in progress for some time, and continues as of this post. We already have copying to and from APFS volumes working "in the lab", as it were, and testing is ongoing.

The bad news is I'm not confident enough to say we're going to release our APFS support day-and-date.

I know this kind of hedging is disappointing. But it's important to note that Apple still hasn't released any documentation on the "proper" way to create a bootable APFS volume. An example of what they have in mind was released for the very first time when the High Sierra developer release came out a few months ago, but that's it. We basically have to make an educated guess about what they want.

We've designed and implemented that, and it's significantly different than HFS+'s boot setup, with various special partitions dedicated to specific purposes (even a separate VM volume!), and entire new volume management system, etc.

So, we have both copying and boot working, and we're testing it carefully to try to cover all of the various permutations that can occur. Because no guidance or documentation is available, and the process is all reverse-engineered from existing volumes, it's difficult to know what might happen in the future...and protecting against mistakes, and informing users what their potential actions mean, is really critical.

For example, what happens if you do an "Erase, then copy" from an HFS+ volume to an APFS volume? In our current version, we match the format of the source when we erase. But, HFS+ can't be in an APFS container. So, we'd have to convert the container to a regular GUID partition. And since there might be other APFS volumes in that container, you'd end up destroying them.

Not good. And that's just one case.

So, we're being cautious, knowing that users who have continually followed our advice (namely more backups are always better than fewer, and use more than one backup program, such as SuperDuper! and Time Machine rather than either on its own) will still be covered by Time Machine if they jump the High Sierra update as soon as it becomes available.

But what about HFS+?

Yes, making a backup from APFS to HFS+, and booting off that, can work as it always has (once our APFS support is released). And HFS+ to HFS+ works as expected as well, save for a few small issues in 2.9.1.

In particular, Apple has further tightened its System Integrity Protection process, and is completely denying access to some files on the startup volume, even when copying to a non-startup volume. We consider those errors ("Operation not permitted") to be fatal in 2.9.1, and so we stop. We have a simple, preference-based workaround for this that we've provided to people during the beta on request, and 2.9.2 has it built-in. (This is the kind of thing I'm talking about when I said "it's difficult to know what might happen"--we didn't know what could happen with SIP, and so we planned for possible changes.)

But since APFS is, again, basically undocumented... what could that backup be missing? How will changes like filename normalization affect future copies if a dot-update modifies behavior? How do you make a snapshot, since that is obviously intended to be a better source for a backup? And do androids actually dream of electric sheep?

These are the kinds of things that have been keeping us awake at night at Shirt Pocket HQ. I feel like I've aged as much as a two-term President.

Anyway, we're grinding through this all as quickly as we can. We don't want to finish until we're sure we have the shipping bits, because, unlike with earlier OS versions, we're dealing with an entire new file system. We'd rather be late than wrong.

We're probably not wrong, but we want to be sure.

Automatic conversion

Speaking of being sure, one of the scariest part of High Sierra is the fact that, if you have an SSD, you'll have no choice: you're going to be converted to APFS, whether you like it or not. Apple is obviously confident about this process, or they wouldn't do it, but even if the conversion is successful, it's important to note that while that means it worked from their point of view -- conversion accomplished! -- this changeover won't be without pain.

  1. Your existing, valuable low-level tools, such as Disk Warrior, will instantly be rendered useless. In a pinch where Disk Utility can't fix it? Tough luck.

  2. Want to host an HFS+ volume on your drive? You can't in an APFS container.

  3. APFS doesn't seem to be faster than HFS+ (which is not to say it won't ever be, or that it won't be more stable...a low bar, I know). That cool demo where copying a whole directory is instantaneous? That's because the data isn't really being copied. It's being referenced, which is, of course, fast. Copying happens when you modify, so it's basically being done "lazily".

    But think about it. That also means that if you made a copy of your data "just in case", and you developed a bad spot on the drive, all copies of the file are now damaged, because they share the same data. Disk damage can now cascade across far more files than before, because you can't tell what's shared. Even snapshots can't save you if they're referencing the same bucket of damaged bits.

  4. So many other things.

There are going to be growing pains here, and a lot of it will be for long time developers who have been doing invaluable work for years, and unlike us, they have to start again from scratch. Need I say they deserve your support and encouragement?


I'm also getting a lot of mail about our 64-bit plans, since there's been a pile of confusion coming out of the WWDC announcements, so let me try to set things straight.

High Sierra works fine with 32-bit apps. Come January, the App Store will stop accepting 32-bit store apps. And, at some point in the future, Apple will stop supporting 32-bit apps.

Now, for most apps, there's really no advantage to being 64-bit (save for some really minor system-wide memory benefits, which—frankly—were the other way around when 64-bit APIs were introduced, and no one complained about that). So for many developers this will be a lot of unnecessary work, with no end-user benefits.

All that said, while there's no rush to do so (they're not phasing out 32-bit for a while), our full High Sierra release will be 64-bit, so you can rest easy, knowing that we'll be ready for the actual phase-out well before it happens.

Should I Update to High Sierra?

I think I usually tell people to "take it slow" with an entirely new OS version. While there have been "huge win" updates in the past (10.6 is a great example), High Sierra isn't one of those.

Rather, while it may be a good (or even great) update over time, it also has the potential to destabilize things far more than anything that's come before. It's going to be hard to judge its impact until its wide release, and even then, it'll be a while.

If you're a normal user, I would strongly encourage you to not update to High Sierra right away. Let others take the risk. Wait until things calm down and the initial problems, which are inevitable, are fixed. Continue doing what you've been doing before High Sierra: you're not missing anything of significance.

Apple's going to be OK if their "adoption graph" doesn't go straight up in the air.

After all, why should you be a statistic when you have work to do?

But I Want to Update Right Away


I Insist on Updating Immediately!

Sigh. OK. But don't say you haven't been warned: we don't all float down here.

Before you update, use SuperDuper to make a full backup or two. Check your backup by starting up from it. Then, unplug the backup drive from your Mac and put it somewhere safe.

As I've recommended elsewhere, you should be making multiple backups with other programs as well, including Time machine. So, after you update, continue to use Time Machine to back up. Given it's basically written by the same team as APFS, and Apple knows what is and isn't possible, even when they don't document it externally, this is your best bet to start with.

If you need to roll back to your previous OS, you cannot just use Smart Update. In fact, you also can't use Erase, then copy, because your internal drive has been converted to a storage scheme that won't work with anything earlier than High Sierra.


So, after starting up from your SuperDuper backup, use Disk Utility to erase the drive you want to restore to, by selecting the drive hardware above the volume, not the volume itself. That will roll you back to something that can properly host HFS+ and boot pre-High Sierra releases. You can then restore your SuperDuper! backup normally, using "Restore - all files" and "Erase, then copy" or "Smart Update".

But How Do I Back Up?

For the moment, as I said above, use Time Machine. Apple's teams know the details of APFS, and as such Time Machine isn't in the "limbo" we're in with regard to ensuring things are as they should be. Remember, disk space is cheap, and I know I say this too much, but it's true: no one was ever sad they had too many backups.

If you are running High Sierra with HFS+ (namely, if you have a spinning disk or Fusion drive), our just-released SuperDuper update will work fine. Use that in addition to Time Machine.

Our full, APFS-supporting version (with some other surprises) will be out as soon as we can get it finished. And we'll have a public beta when we're confident enough to put it in your hands.

This is Going to Cost Me a Ton, Isn't It.

Actually, no. Since 2004, we've never charged for SuperDuper updates, and our High Sierra update will be free of charge as well.

Clearly, we were dropped on the head as babies.


So there you go. I'll be back relatively soon with more.